The invention relates to an intake device containing a manifold, at least one air intake passage, an air intake tube for each passage connected to the respective air intake passage, and an adjusting unit.
A device for the continuous variation of the length of the air intake tube of an internal combustion engine is disclosed in DE 36 08 310. The device comprises a stationary housing serving as a manifold in which a hollow cylindrical rotor body is disposed for rotation, the interior of which is connected to the air intake tube through a connection opening. Ducts separated from one another are defined between the outer circumference of the rotor body and the inner wall of the housing in the radial direction and between the sealing walls in the axial direction, and their effective length is determined by the rotational position of an outlet opening in the rotor body wall, which leads to the interior of the rotor body. On the other hand, each duct leads to an inlet opening of an intake passage leading to each cylinder of the internal combustion engine. Rotation of the rotor body varies the effective length of each duct according to the speed of the internal combustion engine at full load.
In this device, however, the intake duct length is limited by the maximum possible rotor body circumference. Furthermore, upon issuing from the rotor body the fluid is extremely deflected.
It is the object of the invention to provide an intake device which make it possible to achieve long intake duct lengths.
Another object of the invention is to provide an intake device which requires less deflection of the aspirated air than prior art devices.
These and other objects of the invention have been achieved by providing an air intake system for an internal combustion engine, comprising an air intake manifold wherein a portion of the air intake manifold is divided into a plurality of air intake channels, each of the air intake channels being connected at one end to a respective air intake tube, and an adjusting member arranged to extend into the air intake manifold, the adjusting member being movable between a first position in which the air intake channels open to each other, whereby the effective lengths of the respective air intake tubes are shortened, and a second position in which the air intake channels are separated from each other, whereby the effective lengths of the respective air intake tubes are lengthened.
In accordance with another preferred aspect of the invention, the objects are also achieved by providing an air intake apparatus comprising a manifold, at least one air intake channel in the manifold, an air intake tube connected to each respective air intake channel, and an adjusting unit, wherein the adjusting unit comprises a movable adjusting element which extends into the manifold; wherein the manifold, the at least one air intake passage, and the adjusting element are arranged axially parallel; and wherein the at least one air intake passage is formed by the manifold and the adjusting element.
The intake device according to the invention is advantageously able to achieve great intake lengths with only slight deflection of the medium entering it and deliver it to an internal combustion engine.
The intake device comprises a manifold which envelops a manifold chamber and forms a portion of the intake channels or passages. Into this manifold an adjusting unit extends which is mounted in guides provided therefor and which together with the manifold forms the intake channels or passages. The adjusting unit is mounted in the container in a sufficiently sealed or gas-tight manner that the individual intake passages are separate. The separation of the passages from one another can be accomplished by the interaction of the container with the adjusting unit. Each intake channel or passage, which is to be understood as the adjustable length, is connected to an intake tube which has an invariable length. The intake tube opens into a cylinder of the internal combustion engine. The manifold, the adjusting unit and the intake channel or passage are arranged axially parallel. Since the intake device is to be placed in different installation spaces it can follow many different spatial curves, with the spatial curves of the intake passages and the adjusting unit running parallel. The adjusting unit of a straight embodiment can be constructed of a rigid or stiff material. In curved embodiments, to assure proper assembly, the adjusting unit may either be made of flexible material or of material provided with solid inserts, or of stiff material with flexible inserts. In some embodiments it may be desirable to use a multi-part adjusting unit or a plurality of adjusting units in order to assure proper assembly and operation or to achieve certain effects. The manifold can be made as a blow-molded plastic part, or in the case of complicated forms, it can be made by a core melting process.
In accordance with one preferred embodiment, the adjusting unit has portions in which it forms a surface of contact with the manifold. The adjusting unit is arranged so that it is displaceable relative to the manifold. When the adjusting unit is shifted to extend into the interior of the manifold, the manifold chamber is reduced and the effective passage length of the combined tubes and channels is lengthened. By displacing the adjusting unit in the opposite direction the manifold chamber in the manifold is increased and thus the air intake passage length is reduced. The external volume of the manifold is constant; the intake passage length is thus variable and can be adjusted to match the state of operation of the internal combustion engine. To be able to fix preferred settings precisely, e.g. for certain rotatory speeds, rotary or sliding sleeves can be provided which have openings which fix the adjusting unit at the desired position.
In accordance with another preferred embodiment of the invention, the adjusting unit can be shifted by translation. In this embodiment, the adjusting unit is retracted or drawn axially out of the manifold to a certain length, and then the intake passage length is shortened and the size of the manifold is enlarged by this amount. When the adjusting unit is moved inwardly into the manifold the intake passage length is increased by the amount of the inward movement.
One advantageous embodiment of the invention is a xe2x80x9cclover-leafxe2x80x9d arrangement of air intake passages around an adjusting unit. This construction results in an equal distribution of pressure in the manifold. With this arrangement a compact structure is possible, since the wall of each intake channel or passage also forms in part the wall of the adjacent intake channel or passage.
In one preferred embodiment, the adjusting unit may advantageously be formed from a plurality of interconnected segments. With this type of construction the adjusting unit, after being drawn out of the manifold, can be reversed or wound up. For this purpose, springs may be used as connecting means, whose spring rates can be varied individually depending on the requirements of the given situation. Another possibility for joining the segments is to use flexible synthetic resin members, especially elastomers, or to use mechanical joints, such as ball joints.
Another embodiment of the invention involves the use of a adjusting unit which remains mostly in the manifold and which is formed by segments joined together by springs. The successive springs have a stiffness which increases from the manifold chamber toward the air intake tube. The springs are stretched by pulling on one end of the adjusting unit. The spring with the least stiffness is the first to stretch. The segments thus move apart from one another and the air intake channels or passages are provided in this area with a connection through which air can pass. The greater the force with which the adjusting unit is pulled, the greater is the number of segments that open a connection between the channels or passages. Since air can pass through these connections, the effective length of the air intake channel is shortened to the range in which the segments tightly adjoin one another. The points of contact between the individual segments can be of different kinds. The segments can have blunt ends which abut against one another, in which case a sufficient sealing of the individual intake passages from one another must be assured. Another possibility is the use of telescoping segments which are guided into one another and when opened have gaps which short-circuit the air intake channels or passages.
According to another embodiment of the invention, the air intake passages are sealed from one another along their axial lengths by a gasket, resulting in a better charging of the cylinders. The gasket can be in the form of a sealing cage comprising a plurality of sealing surfaces, or the gasket can be configured as an insert for individual sealing surfaces. An inlaid gasket can be installed in the adjusting unit as well as in the manifold.
One advantageous and low-cost variant is the manufacture of the manifold by the injection molding of plastic. In this case curvatures can be achieved, but attention must be paid to the stripping of the parts from the molds. In the case of complicated shapes the manifold can have several parts which are then welded together with air-tight joints.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either individually or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.